Momeni-Moghaddam Hamed, Goss David A, Sobhani Mina
Health Promotion Research Center, Zahedan University of Medical Sciences, Zahedan, Iran.
Clin Exp Optom. 2014 Jan;97(1):36-42. doi: 10.1111/cxo.12074. Epub 2013 Jun 27.
The neurological linkage of vergence and accommodation is a factor which can affect accuracy of accommodation, is in turn associated with symptoms of near-related visual discomfort. The purpose of this study was to compare the accommodative response under monocular and binocular conditions in symptomatic and asymptomatic participants with different near phorias.
Seventy students at Zahedan University of Medical Sciences, Iran (mean age: 21.2 ± 1.7 years; age range: 18 to 25 years) participated. The participants were divided into symptomatic and asymptomatic groups according to the convergence insufficiency symptom survey questionnaire score. The type and magnitude of the near dissociated phoria were determined using the prism neutralised cover test. The accommodative lag was measured by the 'monocular estimate method' (MEM) retinoscopy, at first under binocular and then monocular conditions. Testing distance was 40 cm.
The accommodative lag in exophoric participants was lower under binocular conditions compared to monocular and in esophoric participants greater under binocular than under monocular conditions. The binocular accommodative response (AR) was greatest in participants with high exophoria at near vision and least in participants with esophoria at near vision (p < 0.001; one-way analysis of variance). The difference between binocular lag and monocular lag was significantly greater in symptomatic participants than in asymptomatic participants in both exophoria (p < 0.001) and esophoria (p = 0.009) (independent samples t-test).
The near binocular accommodative response was related to near heterophoria. Higher levels of vergence accommodation, resulting in differences in lag under monocular and binocular conditions, may be a factor in near point asthenopia.
集合与调节的神经学联系是一个会影响调节准确性的因素，进而与近视力相关的视觉不适症状有关。本研究的目的是比较不同近隐斜的有症状和无症状参与者在单眼和双眼条件下的调节反应。
伊朗扎黑丹医科大学的70名学生（平均年龄：21.2±1.7岁；年龄范围：18至25岁）参与了研究。根据集合不足症状调查问卷得分，将参与者分为有症状组和无症状组。使用棱镜中和遮盖试验确定近分离隐斜的类型和程度。通过“单眼估计法”（MEM）视网膜检影法测量调节滞后，首先在双眼条件下，然后在单眼条件下进行测量。测试距离为40厘米。
外隐斜参与者在双眼条件下的调节滞后比单眼条件下低，内隐斜参与者在双眼条件下的调节滞后比单眼条件下高。近视力外隐斜程度高的参与者双眼调节反应（AR）最大，近视力内隐斜的参与者双眼调节反应最小（p<0.001；单因素方差分析）。在有症状参与者中，外隐斜（p<0.001）和内隐斜（p=0.009）情况下双眼滞后与单眼滞后之间的差异显著大于无症状参与者（独立样本t检验）。
近视力双眼调节反应与近隐斜有关。更高水平的集合调节导致单眼和双眼条件下的滞后差异，可能是近点视疲劳的一个因素。
